Apparatus and method for rf grounding of ipvd table

Abstract

An IPVD source assembly and method is provided for supplying and ionizing material for coating a semiconductor wafer. The assembly includes a process space containing a plasma and an electrostatic chuck moveable in to and out of the process space. The chuck is configured to support the semiconductor wafer. The assembly further includes a first shield in electrical communication with a table and a second shield. The first shield is configured to shield at least a portion of the electrostatic chuck when the chuck is in the process space and the second shield is configured to shield at least a portion of a space below the electrostatic chuck and the process space. A conducting element electrically connects the second shield to the table to substantially prevent a formation of a second plasma in the space below the electrostatic chuck and the process space.

1 . An IPVD source assembly for supplying and ionizing material for coating a semiconductor wafer, the assembly comprising:
 a process volume containing a plasma;   a chuck moveable with a table in to and out of the process volume, the chuck configured to support the semiconductor wafer;   a first shield electrically insulated from the chuck and in electrical communication with the table, the first shield configured to shield at least a portion of the chuck when the chuck is in the process volume;   a second shield configured to shield at least a portion of a space below the chuck and the process volume; and   a conducting element electrically connecting the second shield to the table to substantially prevent a formation of a second plasma in the space below the chuck and the process volume.   
   
   
       2 . The IPVD source assembly of  claim 1  wherein the conducting element is a flexible strap. 
   
   
       3 . The IPVD source assembly of  claim 2  wherein the flexible strap is composed of copper. 
   
   
       4 . The IPVD source assembly of  claim 2  wherein the flexible strap is about 100 mm wide. 
   
   
       5 . The IPVD source assembly of  claim 1  wherein the conducting element is a first conducting element, IPVD source assembly further comprising:
 a second conducting element electrically connecting the second shield to the table to substantially prevent a formation of a second plasma in the space below the chuck and the process volume, the second conducting element spaced apart from the first conducting element.   
   
   
       6 . The IPVD source assembly of  claim 5  wherein the first and second conducting elements are symmetrically spaced apart. 
   
   
       7 . The IPVD source assembly of  claim 1  wherein the first shield is in electrically communication with the table through an RF coupling device. 
   
   
       8 . The IPVD source assembly of  claim 1  further comprising:
 a base in electrical communication with the table and the conducting element.   
   
   
       9 . The IPVD source assembly of  claim 8  further comprising:
 a support ring in electrical communication with the second shield and the conducting element, the support ring spaced from the base.   
   
   
       10 . The IPVD source assembly of  claim 9  wherein the support ring is in electrical communication with the second shield through an RF coupling device. 
   
   
       11 . The IPVD source assembly of  claim 9  wherein the support ring maintains electrical contact for the electrical communication and is spaced from the base by a spring. 
   
   
       12 . The IPVD source assembly of  claim 9  further comprising:
 a third shield in electrical communication with the base, the third shield in electrical communication with an extension of the support ring through an RF coupling device.   
   
   
       13 . An IPVD source assembly for supplying and ionizing material for coating a semiconductor wafer, the assembly comprising:
 a process volume containing a plasma;   a chuck moveable in to and out of the process volume, the chuck configured to support the semiconductor wafer; and   a shield in electrical communication with a table and with a chamber wall defining a portion of the process volume, the shield configured move in to and out of the process volume with the chuck and to shield at least a portion of the chuck when the chuck is in the process volume;   the shield further configured to shield at least a portion of a space below the electrostatic chuck and the process volume and substantially prevent a formation of a second plasma in the space below the chuck and the process volume.   
   
   
       14 . The IPVD source assembly of  claim 13  wherein the shield is in electrical communication with the table through an RF coupling device. 
   
   
       15 . The IPVD source assembly of  claim 13  wherein the shield is in electrical communication with the chamber wall through an RF coupling device. 
   
   
       16 . A method of substantially preventing formation of a plasma in a pumping volume, the method comprising:
 providing electrical connection between a chamber shield that surrounds a wafer support to reduce a potential difference between different return RF current paths.   
   
   
       17 . The method of  claim 16  wherein providing the electrical connection includes:
 electrically connecting a first shield to a table; and   electrically connecting a second shield to the table to substantially prevent a formation of a potential difference between the first and second shields,   wherein a first RF current return path forms along a surface of the first shield to a surface of the table, and   wherein a second RF current return path forms along a surface of the second shield to a surface of the table.   
   
   
       18 . The method of  claim 17  wherein the first current return path forms between surface of the first shield and the surface of the table through an RF coupling device. 
   
   
       19 . The method of  claim 17  wherein the second current return path forms along a conducting element electrically connecting the surface of the second shield to the surface of the table. 
   
   
       20 . The method of  claim 19  wherein the second current return path further forms along a surface of a base between the conducting element and the surface of the table. 
   
   
       21 . The method of  claim 16  wherein providing the electrical connection includes:
 electrically connecting a shield to a table and to a chamber wall to substantially prevent a formation of a potential difference between the shield and the chamber wall,   wherein a first RF current return path forms along a surface of the shield to a surface of the table, and   wherein a second RF current return path forms along a surface of the chamber wall the surface of the shield then to the surface of the table.